The annexed engravings represent a mercury steam gauge, invented by Josephus Ech-ols, of Columbus, Ga., who has taken measures to secure a patent. The important features of the improvement consist in so constructing the gauge that a very long heavy column of mercury may be used in a small space to exert its pressure upon the steam in the boiler. Figures 1 and 2 are each sectional elevations of the gauge, connected with portions of a steam boiler, one view being taken from the end of the boiler, and the other from the side. A is the boiler, and 8 is an iron pipe, which may be of a length and size required, according to the pressure of the steam per square inch, for 125 lbs. pressure, say 41 feet long, and 1-4. inch diameter; this pipe or tube is folded up, as shown in the engravings, and may be made to occupy but a very small amount of space; its convolutions may assume a square, round, or any other desired form, or any required height. A suitable case may surround this gauge, resting upon the boiler, as shown in the engravings. The light portions of the tube, as at 3 and 5, represent mercury, and the darker, as at 4 and 6, repre-I sent oil or water introduced between the columns of mercury; 1 and 2 represent the steam from the boiler which presses directly upon the column of mercury, shown at 3, which column, in turn, presses upon 4, of oil or water, 4 again upon 5, and 5 Upon 6, and so on, during a greater or less number of convolutions until the pipe arrives at the steam indicator, which is simply a float with a vertical rod, C, attached, which passes over a graduated scale or by the side of a graduated disc plate, as represented. It should be observed that the columns of water or oil, occupy the whole of the upper half of all the convolutions of the tube, except the end, where the steam is admitted, and the lower half of the same is occupied by mercury when there is no pressure in the boiler; when the pressure is added the water and mercury assume the form repre-serite!. It will be perceived that the length of a!) the columns of mercury added together will b the amount of resistance to the pressure of the steam, as though the whole were1 a single column of meiciiry of the length, of all these added together : this will, no doubt, operate satisfactorily, and is a vpvy good invention. Further information may be obtained by letters addressed to the inventor. The President has approved of Captain Meigs's plan for an aqueduct to supply Washington and Georgetown with water, capable of supplying one hundred millions of gallons per day; the work will be prosecuted with vigor. The Washington correspondent of the New York Journal of Commerce, states that the grave of James Madison, twice President of this Republic, cannot now be recognized.— This is a shame.